1. Field of the Invention
The present invention relates to a lot transporting system between a plurality of stations, i.e., areas, each including a plurality of manufacturing equipments.
2. Description of the Related Art
For example, in a semiconductor manufacturing factory, various kinds of semiconductors are manufactured in parallel, thereby necessitating various manufacturing equipments each specific to one manufacturing step (process). For example, there are approximately 100 to 700 manufacturing processes in one factory. Also, the same lot is often repeatedly processed by the same manufacturing equipment.
In a prior art lot transporting system, a plurality of stations each having a plurality of the same kinds of manufacturing equipments are located at different sites, which will be later explained in detail. Therefore, in this case, each station can usually be defined by its corresponding manufacturing process. As a result, after a manufacturing process performed upon a lot is completed, the next manufacturing process is determined, so that a cart or the like moves this lot to a station specific to the next manufacturing process.
However, in recent years, more manufacturing equipments are installed at the stations without increasing the area thereof, to thereby enhance the manufacturing efficiency. As a result, different kinds of manufacturing equipments are installed at one station, in other words, the same kind of manufacturing equipments are dispersed at a plurality of stations. Further, very highly integrated semiconductors have to be processed by only specialized manufacturing equipments.
Therefore, it is complex to transport lots between the stations, and as a result, the transportation of lots between the stations is actually carried out by hand, to thereby deteriorate the efficiency of transportation of lots, thus increasing the manufacturing cost.